Neuroanatomy Unit III Sect. I

Going clear back to the beginning of Unit III and working my way through. Hopefully I've made it easy to understand where I'm at.


 Name three main functions of nervous system.
Sensory input- gathering information
Integration- interpretation
Motor output- making the body respond to those stimuli

 Describe anatomical organization of nervous system (central and peripheral) and
its components.
Central Nervous System (CNS)- brain and spinal cord
Peripheral NS- everything that used to communicate with the brain and spine

 Describe physiological organization of peripheral nervous system (afferent, efferent). Explain the role of afferent division of PNS and compare its visceral and somatic components. Explain the role of efferent division of PNS and compare its autonomic (visceral) and somatic components. Name two branches of autonomic nervous system and explain their roles in regulation of body functions.
PNS has two parts:
Afferent- carrying impulses to the CNS, has both conscious and unconscious components
Efferent- carrying impulses to the PNS, also has intentional (ie somatic) and automatic parts
The autonomic part is then split into sympathetic (emergencies) and parasympathetic (relaxation) systems

 Describe the cellular components of a neuron (body, axon, dendrite, axon hillock
and synaptic knob).
Neuron body- contains nucleus and organelles, conducts charge to some degree
Axon- carries impulse away from neuron body
Dendrite- carries impulse into neuron body
Axon hillock- where axon begins, sending off the initial charge
synaptic knob- end of axon, releasing neurotransmitters when activated

 Describe three types of neurons based on their structure, explain their function.
Unipolar- axon divides into two, found in the brain and spine
Bipolar- has both a long axon and a long dendrite, found in eye and nose (sensory)
Multipolar- many small dendrites and a long axon, most common

 Give functional classification of neurons (motor, sensory and interneurons). Give
example using reflex arc.
Word for word:
Sensory- afferent neurons
Motor- efferent neurons
Interneurons- associated neurons
Touching a stove triggers reflexive arch, the hard wired, unconscious response necessary when an immediate response is required.

 Explain the following terms: electricity, voltage (potential difference), current, resistance, polarity, electrical gradient, and chemical gradient.
Electricity- stationary or moving electrons and protons
Voltage- electric potential: the difference in electrical charge between two points in a circuit expressed in volts
Current- a flow of electricity through a conductor; "the current was measured in amperes"
Resistance- a material's opposition to the flow of electric current
Polarity- having a pair of equal and opposite charges
Electrical gradient- the difference in electrical charge (valence) across the membrane
Chemical gradient- a difference in the bulk concentration of an ionic species on either side of the membrane

 Name different types of plasma membrane ion channels and explain how they function; give examples. Compare intracellular and extracellular concentration of sodium, potassium and chloride ions. Comment on the membrane permeability for these ions at rest. Explain physiological bases for resting membrane potential.
What ion is mostly responsible for it? Is the resting membrane potential a truly
restful state or is it an active process? What is the role of sodium-potassium
pump in this process? What is the numerical value of resting membrane potential
in a neuron?
There are passive and active ion channels. Passive means that the ions flow with the gradient (electrical and chemical). Most of the time the sodium (Na) and potassium (K) are flowing in these directions. Since these ions (Na and K) they don't want to go up the gradient, they have to be actively transported by pumps in order to reset the cell.
Normally there is too much K inside the cell and too much Na outside the cell. This is what creates the gradients.
Potassium is responsible for the resting membrane potential because it flows out more than sodium flows in.
Maintaining a resting state requires a good effort because these two ions are always trying to slip in/out and having to be pumped back.
Resting membrane potential= -70mV